Who would win?

An ongoing discussion at our house is "who would win a battle between," with it a given that each competitor uses his natural weapon.

Thing One: Who would win between Count Dooku and General Grievous?
Dapper Dad: Count Dooku. Who would win between Mace Windoo and Ki-Adi-Mundi?
Thing One: Mace Windoo. Who would win between Grito and General Grievous?
Dapper Dad: That's easy. General Grievous.
Me: Definitely.
Thing One: Why?
Me: Because he's really tough. Who would win between The Emperor and Darth Vader?
Thing One: I think Darth Vader. Who would win between the Emperor and the Umpire?